1. Technical Field
The present invention relates to the electrostatic discharge (ESD) technology field and, more particularly, to an ESD protection circuit and a display apparatus using the same.
2. Description of the Related Art
Conventional liquid crystal display apparatus mainly employs thin-film transistor (TFT) diode, metal-insulator-metal (MIM) diode, lightning-rod design or impedance in series to prevent the main circuits of the liquid crystal display apparatus from being destroyed by the electrostatic discharge. For example, the conventional liquid crystal display apparatus can employ one of the aforementioned four manners to prevent a gate driver of the liquid crystal display apparatus from being destroyed by the electrostatic discharge or to prevent a pixel circuit of the liquid crystal display panel from being destroyed by the electrostatic discharge. The following will describe the above four manners in detail.
FIG. 1 is a schematic view of a conventional liquid crystal display apparatus. Referring to FIG. 1, the liquid crystal display apparatus 100 comprises a display panel 110, a plurality of ESD protection devices 120 and a shorting ring 130. The display panel 110 comprises a plurality of pixels 112, a plurality of gate lines 114 and a plurality of source lines 116, and each of the pixels 112 is electrically coupled to one of the gate lines 114 and one of the source lines 116. Furthermore, each of the ESD protection devices 120 is electrically coupled to the shorting ring 130, and each of the ESD protection devices 120 is electrically coupled to one of the gate lines 114 and the source lines 116.
In addition, each of the ESD protection devices 120 is composed of a plurality of transistors 122, and each of the transistors 122 is implemented by a thin-film transistor (TFT) electrically coupled by a specific manner. The so-called TFT diode is formed by a TFT which is electrically coupled by the specific manner. The ESD protection device 120 shown in FIG. 1 has the disadvantage that the threshold voltages Vth of the TFTs 122 of the ESD protection device 120 will shift after the ESD protection device 120 operates for a long time. This will affect the conducting capability of the TFTs 122.
FIG. 2 is a schematic view of another conventional liquid crystal display apparatus. In FIGS. 2 and 1, the objects of uniform labels represent the same element. Referring to FIG. 2, compared with the ESD protection device 120 shown in FIG. 1, each of the ESD protection devices 220 of the liquid crystal display apparatus 200 is implemented by the MIM diode. The ESD protection device 220 shown in FIG. 2 has the disadvantage that the conducting capability of the ESD protection device 220 is bad when the ESD is small, and the ESD protection device 220 is easily to breakdown to lead to a permanent damage when the ESD is large.
FIG. 3 is also a schematic view of another conventional liquid crystal display apparatus. In FIGS. 3 and 1, the objects of uniform labels represent the same element. Referring to FIG. 3, compared with the ESD protection device 120 shown in FIG. 1, each of the ESD protection devices 320 of the liquid crystal display apparatus 300 is implemented by designing a part of the metal region of a gate line 114 or a source line 116 with a part of the metal region of the shorting ring 130 to form a lightning-rod pattern. The ESD protection device 320 shown in FIG. 3 has the disadvantage that the ESD protection device 320 is also easily to be damaged when the ESD is large.
FIG. 4 is a schematic view of still another conventional liquid crystal display apparatus. In FIGS. 4 and 1, the objects of uniform labels represent the same element. Referring to FIG. 4, compared with the ESD protection device 120 shown in FIG. 1, each of the ESD protection devices 420 of the liquid crystal display apparatus 400 is implemented by a resistor. And the liquid crystal display apparatus 400 does not adopt the shorting ring 130 shown in FIG. 1. In addition, each of the gate lines 114 is electrically coupled to the gate driver (not shown) through a corresponding ESD protection device 420, and each of the source lines 116 is electrically coupled to the source driver (not shown) through a corresponding ESD protection device 420. The ESD protection device 420 shown in FIG. 4 has the disadvantage that the loading of the gate driver and the source driver will be increased to lead to poor driving capability after increasing the resistance of the resistor.
In summary, it can be seen that each of the aforementioned ESD protection manners has its disadvantage, and each of the disadvantages may cause the said main circuits to be damaged by the ESD because of the lack of effective prevention. Specifically, the said main circuits may be completely unable to be prevented from the ESD damage because of the perpetual damage of the ESD protection device. Since the ESD may occur anywhere, it is necessary to provide an ESD protection device with a stable and reliable performance. In addition, the provided ESD protection device must not to increase the loading of the gate driver and the source driver.